a. Field of the Invention
This invention relates to a pipeline inspection apparatus and to a method of inspecting the internal surfaces of a pipeline using a pipeline inspection apparatus.
b. Related Art
Pipeline Inspection Gauges (Pigs) are known for use in pipeline cleaning and inspection. Typically a Pig is inserted into a pipeline at a particular point (a launching station), is propelled along the pipeline by the flow of fluid through the pipeline and is then removed from the pipeline at a specific point further downstream (a receiving station).
The use of Pigs allows pipes to be cleaned and the condition of the pipes to be inspected without stopping the flow of fluid through the pipe.
An intelligent Pig, or Smart Pig, can be used to collect data, typically about the condition of the pipeline, while it is travelling along the pipeline. Some prior art devices, for example, have incorporated sensors to detect pipe defects and corrosion. Data from these sensors are then analysed once the Pig has been retrieved from the pipeline. In order to determine the position of any defect within the pipeline, Pigs often also incorporate some form of location monitoring system, or the location of the Pig is monitored by sensors located above-ground.
Pipelines often contain fluids at a high temperature, and the fluids may be highly acidic or basic. For these reasons it is necessary to carefully protect any sensors and electronics that are contained within the Pig.
It some circumstances it is desirable to capture images of the internal wall of a pipeline. Prior art systems have been developed that can travel along a length of pipeline and which incorporate a video camera. These systems mount the camera on a wheeled apparatus, or tractor, to enable the speed of passage of the camera through the pipeline to be controlled to capture images of sufficient quality for subsequent analysis.
Additionally, these systems incorporate a line or tether linking the camera tractor back to a base station. The tether permits a user to control movement of the camera tractor, permits video images to be streamed back to the base station for observation and permits the camera tractor to be retrieved from the pipeline after use.
It is an object of the present invention to provide an improved pipeline inspection apparatus that overcomes some of the problems with prior art devices.